Solutions of alkali metal silicates



66mm; OR PLASTIC.

Patented June 23, 1936 SOLUTIONS OF ALKALI METAL SILICATES Paul C. Lemmerman and William K. Schweitzer, East Cleveland, Ohio, assignors to The Grasselli Chemical Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Application December 1, 1933, Serial No. 700,614

3 Claims. (Cl. 134-2332) The present invention relates to aqueous solusilicate solutions according to my invention. tions of lkali metal silicates mm Particularly useful are, however, the sulfates amounts of smla't' on products of all hatic alcoobtained from primary alcohols and their oxyhols containing more than '7 carhon atoms in the gen derimcohollc him a co 0 c ra cal. car nr ca contains from 8 to 18 carbon atoms 6 The invention is particularly applicable to s g inclusive. diu r n and gotassium silicate solutions and par- These sulfates form water soluble alkali metal, ticularlyto econcentra solutions of aspecific ammonia and amine salts, e55. ana it E lh the gravity of between about 15 and 60 gg, and to ori'no such s e are most convenientcompositions in which the molecular ratio of ly added to silicatesolutio ns, It will,however, be 10 alkali to silica is between 1 MeO:l.5 SlOz and understood th'ait'thdfee sulfates themselves can 1 MeOz4 SiOz. The addition of small amounts be added to the silicafi solutions which, due to o a s ation product of a higher aliphatic alcotheir alkalinity, form the corresponding salts.

hol greatly modifies the physical properties of The amounts of sulfates which are required to alkali metal silicate solutions of the above commodify tsfirsperuesbr alkali metal silicate solu- 15 positions. tions is relatively small, from of 1% to 1% The sulfation products referred to herein are based on the weight of the solution produces the obtained by reacting with concentrated sulfuric maximum effect, larger amounts can naturally acid, oleum', chlorsulfonig acid or other sum? be added but for economical reasons such larger in d eri'vatives of strongly sulfonatingm amounts are entirely unnecessary. 20 ties u on all hati'c alcohols or ester s con'tai'mn' g We also found that contrary to the experience more than '7 carEn atoms m the alcoholic ramwith ordinary electrolytes the sulfates of higher cal. According to e es experimental evidence alcohols do not precipitate silica from the silicate available the sulfation products of the alcohols solutions, particularly if their amounts contained are sulfuric acid esters of the probable formula in the solutions do not exceed about 2% of the 25 :H W1 e possible production of weight of the solution. Efior amounts of sulfonic acids. When sulfating The properties of the silicate solutions which esters of unsaturated alcoholsthe sulfuric acid are modified to a greater or lesser degree by the melf to""th double bond but the evidence presence of small amounts of the sulfates of highavailable is insuflicient to decide if the products er alcohols are their viscosity, surface tension, 30

are sulfuric acid esters, sulfonicacids or a mixdrying and solidifying characteristics, their peneture TJTsTih compounds. As far as applicability tration into porous or absorbent surfaces whereby in my invention is concerned, the reaction prodtheir properties for adhesive and coating puructs obtained by the action of the sulfuric acid poses are greatly improved.

etc. upon the alcohols or upon the unsaturated Our novel compositions are intended for use 35 esters are entirely equivalent and for purposes of my invention I choose to call these products the sulfates of aliphatic compounds having an alcohgTie'radic-lalfoffmore than 7 carbon atoms, the presence of an aliphatic alcoholic hydro-carbon radical of more than 7 carbon atoms and a salt forming sulfur-oxygen group in the molecule being the determinants for the availability of a given compound for addition to silicate solutions. The higher alcohols'from which the sulfates useful in my invention are derived are, for 1hstance, ole l stearyI, cet 1, 1a 1, mesitoyl, carnaubyl, mel sszl, etc. co cls,the1r es'Efid esters or 'ethers suc as acetyl-oc 1 001101,

s earog year 1 ether, oleo 1'- 'lyEery eher, etc. Similarly other g 'oho'ls' Whl ch can be obtained by hydrogenation of fatty acids and their esters or by high pressure hydrogenation of carbon monoxide are, when sul- 55 fated, very useful addition agents to alkali metal in various fields in which improved spreading,

penetrating and adhesive properties are particularly advantageous. For example, it is known that in applying sound-deadening board, such as fibre board,to sheet metal partitions ordinary sodium silicate solutions will not completely and readily wet the metallic surfaces, whereby a relatively poor bond between the steel and the fibre board is obtained. Our new silicate compositions containing small amounts of a sulfation product of an alcohol having more than 7 carbon atoms will readily wet steel and even painted steel surfaces and when used as an adhesive produce an excellent bond between steel and fibre board.

Similarly in the use of silicate solutions for adhesive purposes in the manufacture of multi; p qrygmsstedlbnemsfmm highly s ed plies. straws that the presence of small amounts of sulfation products of higher alcohols greatly imqthe solutions are mixed with thickening agents such as starch, colloidal clays, Hour, so'"'B'ya can meal or other agents commo'n'ly e ms modify their consistency.

The improvements in adhesive properties of our modified silicate solutions are difiicult of measurement but the changes in surface tension, which is, however, not the only property determining the usefulness of our compositions, can .easily be shown by laboratory tests.

The determination of surface tensions are conveniently made by the standard DuNouy tensionmeter as described, for instance, on page 72 of Laboratory Manual of Colloid Chemistry in 1928, by H. N. Holmes. The figures obtained in such tests are given as dynes per centimeter at 28 C. It was found necessary in using this test on concentrated silicate solutions to dilute with water to prevent the formation of surface films which would otherwise interfere with the tests. The results of the tests shown below were obtained on solutions of a specific gravity greater as than about 35 B. which had been diluted in the proportion of 2 parts by weight of the solution with 3 parts by weight of water.

Another simple laboratory test which gives indications as to the differences in properties between alkali metal silicate solutions free from or containing small amounts of sulfates of higher alcohols consists in dropping a measured amount of the solution upon a metallic, water repellant surface, measuring the surface covered by the solution, drying the solution and remeasuring the surface covered by the dried film. Films from straight silicate solutions show a considerable ified silicate solutions cover substantially the same area as the solution.

The following table gives results of the above two tests made with a 42.5" B. sodium silicate solution of a Nazozsioz ratio of 1:325.

With other sulfates of higher aliphatic alcohols containing more than '1 carbon atoms in the molecule and with other concentrated silicate solutions of the compositions specified, similar reductions of the surface tension will be shown in this test and the above results are merely given as illustrative of the test which can be applied to our modified solutions.

We claim:

1. An adhesive and coating composition comprising an aqueous solution of an alkali metal silicate of a composition between the limits of about 1 Me2O:1.5 Sic: and 1 MezOz4 SiOz in which Me stands for an alkali metal containing not more than about 1% of the weight of said solution of a sulfate of an aliphatic compound containing an alcoholic hydrocarbon radical of more than 7 carbon atoms.

2. An adhesive and coating composition comprising an aqueous concentrated sodium silicate solution of a composition between the limits of about 1 NazO:1.5 S102 and 1 Naa024 S102 containing not more than about 1% of the weight ofsaid solution of a sulfate of an aliphatic compound containing an alcoholic hydrocarbon radical of more than 7 carbon atoms. 3. An adhesive and coating composition comprising an aqueous concentrated sodium silicate solution of a composition between the limits of about 1 NazO:1.5 S10: and 1 NazO:4 SiQ-z containing not more than about 1% of the weight of said solution of a sulfate of a primary alcohol of from 8 to 18 carbon atoms inclusive.

PAUL C. LEMMERMAN.

whereas films obtained from 01].! mod- WILLIA K- SCHWEITZER.

W s f a s... I i 0/ J g a? U C U s 

